WTW09 Teachers Resources - Oregon State Universitycioss.coas.oregonstate.edu/...Resources_Booklet.pdf · of anthropogenic (human-generated) sounds in the oceans. Sound in the sea

High School SMILE Club Activities Winter 2009 Teacher Resources Booklet

SMILE Winter Teacher Workshop Fri 30th Jan 2009

High School SMILE Club Activities Winter

2009

Ocean Science:

What About Whales?

Teacher Resources Booklet

WhaleWorks Satellite Pursuit Whale Watcher

Ocean Color Fishy Tales

Material Compiled by Laura Dover, Marine Resource Management Masters GRA,

SMILE, Oregon State University [email protected]


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Contents Title Page # 1. WhaleWorks Sound in the Sea…………………………………………..................2

Blubber ………………………..........................................7 Whale Feeding Strategies….....................................8 Whale Adaptations Overview...................................11

2. Satellite Pursuit Satellite Tracking…………………………............................17

3. Whale Watcher Gray Whale Migration……….....................................24 Human Impact on Whales......................................29

4. Ocean Color Ocean Color……………………….....................................32

5. Fishy Tales Fish Scales ………………………......................................35

6. Useful Websites……………………………………………………………………………………38 7. Other Resources………………………………………………………………………………….39


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Sound in the Sea

Sound is the vibration of molecules. These vibrations travel in waves, and they travel at different speeds depending on what they are traveling through. Sound travels lowest through gases, faster through liquids and fastest through solids. That’s because the molecules of a liquid are closer together than the molecules of a gas, and the molecules of a solid are even more densely packed than the molecules of gases and liquids. Sound travels through air at a speed of about 340 meters per second (0.2 mile/sec). But underwater, sound travels at approximately 1,600 meters per second (1 mile/sec). Compare this with vision. In most circumstances, on land most mammals easily can see 100 feet ahead. But underwater, visibility is much more limited. An animal using its vision to navigate its way through the ocean needs to move relatively slowly and near the well-lighted surface. Some toothed whales (and other animals, such as bats) use sound to navigate and to locate prey. A whale produces sounds that travel through its melon and out into the water in front of the whale. The whale listens for the echoes that bounce back. This process of sound navigating is called echolocation. Even in dark or murky water, echo-locating whales can interpret the echoes they hear to tell the shape, size, speed and distance of objects in the water. The soft tissue and bone that surround a whale’s ear conduct sound to the ear. In toothed whales, the fat-filled lower jawbone is a good conductor of sound1.

Sounds produced by marine animals, natural processes, and human activities fill the world oceans. Because water is an effective medium for the transmission of sound, both marine animals and people use sound as a tool for finding objects, navigating, and communicating under water.

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1 Taken from Jean-Michel Cousteau Ocean Adventures “Whale Adaptations” http://www.pbs.org/kqed/oceanadventures/educators/pdf/OceanAdv-WhaleAdapt.pdf 2 Image taken from NOAA Ocean Explorer Sound in the Sea Gallery http://oceanexplorer.noaa.gov/gallery/sound/sound.html

Spectrogram of a northeast Pacific blue whale


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Sound travels far greater distances than light under water. Light travels only a few hundred meters in the ocean before it is absorbed or scattered. Even where light is available, it is more difficult to see as far under water as in air, limiting vision in the marine environment. In addition to sight, many terrestrial animals rely heavily on chemical cues and the sense of smell for important life functions (such as marking territorial boundaries). Olfactory cues are restricted in the marine environment. Therefore the sense of smell is much less important to marine species. Underwater sound allows marine animals to gather information and communicate at great distances and from all directions. Many marine animals rely on sound for survival and depend on adaptations that enable them to acoustically sense their surroundings, communicate, locate food, and protect themselves under water.

In addition to the variety of naturally occurring sounds (e.g. breaking waves, lightning, earthquakes) and sounds made by marine animals, there are many sources of anthropogenic (human-generated) sounds in the oceans. Sound in the sea can be a by-product of human endeavors. For example, over ninety percent of global trade depends on transport across the seas and shipping produces a great deal of underwater noise.

All anthropogenic sound is not just a by-product of human activities. Some underwater sounds are intentionally used for a variety of valuable and important purposes. Sonar systems use sound waves to map the seafloor and chart potential hazards to navigation, locate offshore oil reserves, and identify submerged objects. For the scientific community, underwater sound is fundamental in determining the basic properties of the oceans and studying the animals that live there. In addition, acoustics provides an effective means to document and analyze significant natural geologic processes such as earthquakes, volcanic activity, and sea floor slides. It is crucial to use sound to study these processes because they can have profound effects on coastal and island communities worldwide. As we continue to explore the oceans and use marine resources, we must determine the conditions for safe and sustainable use of sound in the sea.

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3 Image taken from NOAA Ocean Explorer Sound in the Sea Gallery

Ocean Acoustics


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Sound is used to study marine mammal distributions by listening to the sounds animals make. Different species of whales and dolphins produce different sounds, such as songs, moans, clicks, roars, whistles, and sighs. Each species is unique in its vocalizations. Scientists can listen for these sounds and track the different marine mammal species, and sometimes even individual animals, while they are producing sound. Passive acoustics also provides information that contributes to conservation management decisions regarding marine mammals, such as monitoring endangered species.

4 Marine animals use sound to sense their surroundings, communicate, locate

food, and protect themselves underwater. They generate sounds to attract mates, defend territories, and coordinate group activities. Marine mammals use sound to maintain contact between mother and offspring, for reproduction, and to display aggression. Fishes produce various sounds that are used to attract mates as well as to ward off predators. Some marine invertebrates, such as spiny lobsters, are thought to produce sound in order to scare away predators.

One of the best known examples of animals that use sound over long distances for reproduction is the song of the humpback whale. Male humpback whales produce a series of vocalizations that collectively form a song. These songs can be heard miles away. Humpback songs are complex in structure and long in duration. Whales have been known to sing the same song for hours.

Reproductive activity, including courtship and spawning, accounts for the majority of sounds produced by fishes. Croakers are renowned for their sound producing ability. During the spawning season, these fish form large groups that vocalize for many hours. These vocalizations often dominate the acoustic environment in which they occur.

Some marine mammals also use sound to locate food and navigate through water. Toothed whales use echolocation to find prey and avoid obstacles. These whales send out sounds that are reflected back when they strike an object. Echolocation functions just like active sonar systems. The echoes provide information

http://oceanexplorer.noaa.gov/gallery/sound/sound.html 4 Image taken from Wikimedia Commons http://commons.wikimedia.org/wiki/File:Toothed_whale_sound_production.png

Sound production in a toothed whale


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about the size, shape, orientation, direction, speed, and even composition of the object. Dolphins have an ability to detect and identify a target the size of a golf ball at a distance of 100 meters (more than the length of a football field).

Marine animals have unique physiologies for producing, detecting, and interpreting underwater sounds. Toothed whales and dolphins (odontocetes) produce a wide variety of sounds including clicks, whistles, and pulsed sounds. These marine mammals pass air through air sacs in their heads to produce sound. The sound is then channeled through fats in the fore- head (called the melon) to the water in front of the animal. The melon helps focus outgoing sound waves into directional beams

5 5 Image taken from NOAA Ocean Explorer Sound in the Sea Gallery http://oceanexplorer.noaa.gov/gallery/sound/sound.html


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Seals, sea lions, walruses, otters, and polar bears live on land at least part of the time and have ears that are similar to terrestrial mammals. Whales, dolphins, and porpoises (cetaceans) that spend their whole lives in the water have developed a different mechanism for detecting sound. In some cetaceans, sound is channeled from their aquatic environment to the middle ear through the lower jaw. Although the inner ear of cetaceans functions in the same way as terrestrial mammals, their inner ear is not part of the skull bone as is the case with most other animals. Special adaptations of the ear structures contribute to the exceptionally high frequency hearing range in toothed whales and the low frequency hearing range in baleen whales.

Fishes produce many sounds, including grunts, croaks, clicks, and snaps, using different mechanisms. Fishes may rub skeletal parts (such as teeth or spines) together to produce sound. This process is similar to crickets rubbing their wings together to make sound. Some fishes produce sounds using sonic muscles located on or near their swim bladder, a process called drumming. The swim bladder radiates the sound driven by the sonic muscle movement. The sonic muscle is the fastest contracting muscle known in vertebrates. Most marine invertebrates known to produce sounds do so by rubbing two parts of their bodies together. The snapping shrimp, however, produces sound in a unique way. Upon closure of its enlarged claw a bubble is formed that collapses, producing a loud popping sound. Sound generated by colonies of snapping shrimp is so prevalent in some shallow water regions that it interferes with the sonar of naval vessels6.

6 Taken from University of Rhode Island’s “Discovery of Sound in the Sea” http://www.dosits.org/downloads/DOSITS_Booklet_low.pdf


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Blubber

Blubber serves several different functions. It is the primary location of fat on some mammals, and is essential for storing energy. It is particularly important for species, which feed and breed in different parts of the ocean. During these periods the species are operating on a fat-based metabolism. Recent research also shows that blubber may save further energy for marine mammals such as dolphins in that it adds bounce to a dolphin's swim.

Blubber is, however, different from other forms of tissue in its extra thickness, which allows it to serve as an efficient thermal insulator, making blubber essential for thermoregulation. Blubber is also more vascularized, or rich in blood vessels, than other adipose tissue.

Blubber has advantages over fur (as in Sea Otters) in the respect that although fur can retain heat by holding pockets of air, the air pockets will be expelled under pressure (while diving). Blubber, however, does not compress under pressure. It is effective enough that some whales can dwell in temperatures as low as -40 degrees Fahrenheit. While diving in cold water, blood vessels covering the blubber constrict and decrease blood flow, thus increasing blubber's efficiency as an insulator. Blubber can also aid in buoyancy, and acts to streamline the body because the highly organized, complex collagenous network supports the non-circular cross sections characteristic of cetaceans7. How does a whale acquire this fat layer? Being mammals, whales suckle their young. A baby gray whale, for example, may drink up to 30 gallons of its mother's milk-which has the consistency of soft margarine-every day! An adult gray whale, on the other hand, may eat tons of crustaceans during a given feeding period. All of this intake is necessary to not only provide the whale with the energy it needs to swim great distances and dive to incredible depths, but to help maintain an essential layer of fatty insulation8.

7 Image and text taken from Wikipedia Article “Blubber” http://en.wikipedia.org/wiki/Blubber 8 Taken from OPB Secrets of the Ocean Realm “The Great Whales” http://www.pbs.org/oceanrealm/intheschool/school5.html


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Whale Feeding Strategies

BALEEN WHALES

Whales are classified into two major groups, toothed or baleen, based partially on feeding strategies. Mysticetes, or baleen whales have specialized structures in their mouth called baleen instead of teeth to help them catch food. Amazingly, the largest animals on earth, baleen whales, survive by eating some of the smallest animals, called zooplankton. Imagine how much zooplankton a 100-foot blue whale must eat! A large Blue whale can eat more than 9,000 pounds (4,100 kilograms) in one day. Every time the whale swallows, over 100 pounds (50 kilograms) can go down its throat. Different Ways Of Feeding: Skimmers:

Some baleen whales feed by sifting plankton directly out of the water. They swim close to the surface with their mouths open. Zooplankton, like copepods, float into the mouth and are caught in the baleen. This type of feeding is best for capturing slow, surface-dwelling zooplankton that cannot swim away from the whale.

Right whales and bowhead whales are skimmers.

Gulpers: These whales have specialized pleats, or folds, in their throats that expand out like a huge bag. They feed by taking huge amounts of water into their mouths, trapping the prey inside. The pleated throat balloons out to hold the water and food. The whale forces the water out past the baleen and the food gets trapped in the baleen. Gulpers are very good at catching fast swimming food, such as krill or small schooling fish.

Blue whales and humpback whales are gulpers.


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Suckers: Bottom-feeding whales travel down to the ocean bottom to feed on small shrimp-like crustaceans, called amphipods. They roll over on one side of their bodies and suck up large mouthfuls of mud. As they travel back to the surface, they squeeze out the mud and water through the baleen to trap the amphipods. These whales often leave large craters along the bottom where they vacuumed up their dinner9.

Gray whales are bottom-feeders.

o Baleen grows throughout a whale's lifetime. The inner edge and tip continually

wears down. o Baleen whales have tooth buds during the embryonic stage. The tooth buds

disappear before birth. o Baleen is sometimes referred to as "whalebone". o Baleen ranges in color from black to yellow to white, depending on the species. o The longest baleen belongs to the bowhead whale. Their baleen grows to over

14 feet long10. TOOTHED WHALES

The second major group of whales are the toothed whales or odontocetes (odont from the Greek word for tooth) and includes dolphins and porpoises. Odontocetes are usually smaller than baleen whales and have one blowhole. Unlike baleen whales, toothed whales are selective eaters. They often hunt down individual animals, such as fish, squid, seals or sea lions, and even birds. Toothed whales have the ability to locate and identify objects by listening for echoes. They echolocate by producing clicking sounds and then interpret the echo that comes back. Echolocation allows odontocetes to determine size, shape, speed, distance, and direction of potential prey and other objects.

Unlike many other animals with teeth, odontocetes do not use their teeth to chew their food. Odontocetes' sharp teeth help them to grab onto their prey. The food

9 Taken from American Cetacean Society curriculum “Baleen Whales” http://www.acsonline.org/education/curriculum/private/curr-baleen.html 10 Taken from SeaWorld Animal InfoBooks http://www.seaworld.org/animal-info/info-books/index.htm


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is swallowed whole or in large chunks. The number and placement of teeth a toothed whale has affects what it eats and how it captures its food. Teeth In Both Jaws

Some toothed whales have teeth in their upper and lower jaws, like humans. Whales with small rows of teeth, such as the Bottlenose Dolphin, eat small, schooling fish. Other toothed whales, such as killer whales, have larger teeth and can hunt down larger fish and marine mammals. Teeth In Lower Jaw Some toothed whales, like the sperm whale, have fully developed teeth on the lower jaw only. Through time, the upper teeth gradually became modified. Sperm whales often feed on squid.

Unusual Teeth

Some toothed whales are very unusual in their dental patterns. Most female beaked whales have no teeth at all, and most males only have two teeth on the lower jaw. And some of these teeth may be so modified as to be useless for feeding. The two teeth on an older male Strap-toothed whale may grow so large as to curve over the mouth and prevent it from opening completely! Fortunately, the whale can still suck squid into its mouth, using its beak and tongue like a vacuum cleaner.

Then there is the male narwhal, with its large (up to 9 feet) tusk. (It only has

two teeth, too, but in their case they are in the upper jaw only). The tusk is actually one of the teeth (usually the left one)! It is obvious that these teeth cannot be used for eating. Scientist believe that these teeth are used in dominance battles, where males use non-lethal fighting to establish their place in their social order. The female narwhal also has two teeth in the upper jaw, but these rarely erupt into tusks11.

11 Taken from American Cetacean Society curriculum “Toothed Whales” http://www.acsonline.org/education/curriculum/private/curr-toothed.html


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Whale Adaptations Overview

Swimming

• A baleen whale swims with up-and-down strokes of its powerful tail flukes. Muscles in the upper and lower regions of the caudal peduncle (tail stalk) provide power.

• The Rorqual whales are more streamlined than other baleen whale families, and they swim fastest of baleen whales. The fastest can reach probably approach speeds of 32 kph (20 mph).

• Other species travel at slower speeds. Gray whales migrate at about 10 to 11 kph (6-7 mph).

• The thick layer of blubber under the skin of a whale results in a streamlined,

fusiform body, making a whale energy-efficient for swimming.

• Orca (Killer whales) are among the fastest swimming marine mammals. They can swim at speeds up to 48.4 kph (30 mph), making them perhaps the second fastest marine mammal next to the Commerson's dolphin, which reaches swimming speeds up to 56 kph (35 mph). Orcas generally cruise at much slower speeds, however, usually from 3.2 to 9.7 kph (2 - 6 mph).

Diving

• Many species of baleen whales feed in relatively shallow areas of the continental shelf. Most are not known for diving regularly to great depths.

o Gray whales make shallow dives of 15 to 50 m (50-165 ft.), but may dive for food as deep as 120 m (390 ft.) in polar feeding grounds.

o Humpback whales dive to at least 148 m (485 ft), and fin whales dive to a maximum of about 355 m (1,165 ft.)

• All marine mammals have special physiological adaptations during a dive. These adaptations enable a baleen whale to conserve oxygen while underwater.

o Baleen whales, like other mammals, have a slower heart rate while diving.

o Orca, like other marine mammals, have a slower heart rate while


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diving. An Orca’s heart rate can slow from 60 beats to 30 beats per minute while diving.

o When diving, blood is shunted away from tissues tolerant of low oxygen levels toward the heart, lungs, and brain, where oxygen is needed most

o Certain protein molecules - hemoglobin and myoglobin - store oxygen in body tissues. Hemoglobin occurs in red blood cells. Myoglobin occurs in muscle tissue. The muscle of baleen whales has twice the myoglobin concentration of the muscle of land mammals

Respiration • Baleen whales breathe through two blowholes on top of the head. A baleen

whale holds its breath under water and surfaces to breathe

o As it surfaces, the whale opens its blowholes and explosively exhales o After exhaling, the whale quickly inhales, then closes the blowholes

before diving o For a gray whale, each exhalation/inhalation takes about two seconds

• Baleen whales typically breathe several times at the surface before submerging

again for several minutes. The number of respirations depends on the whale's activity level. For example, right whales often stay under water for 5 to 15 minutes, then surface and blow five to ten times at 3 to 15 second intervals before diving again

• The visible spout of water that rises from a baleen whale's blowhole is not coming from the lungs, which (like ours) do not tolerate water

o Water that is on top of the blowhole when the powerful exhale begins is

forced up with the exhaled respiratory gases. o Especially in cool air, a mist may form; it is water vapor condensing as

the respiratory gases expand in the open air

• Many baleen whale species can often be identified by the size and shape of the "blow"


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o Right whales have a low, bushy blow o A blue whale's blow may reach 9 m (30 ft.) in the air o A gray whale's blow looks heart-shaped when viewed from directly

behind or in front of the whale o Minke whales sometimes have no visible blow

Thermoregulation

• Baleen whales maintain a core body temperature somewhere between about 36.6 degrees C and 37.2 degrees C (98-99 degrees F). This temperature is similar to that of other large mammals. There is a heat gradient throughout the blubber to the skin.

• A blubber layer just underneath the skin is made of fat cells and fibrous

connective tissue. Blubber insulates the whale from the cold ocean water.

o Blubber makes up 27% of a blue whale's body weight, 23% of a fin whale, 21% of a sei whale, 29% of a gray whale, and 36% to 45% of a right whale.

o The blubber layer can reach a thickness of 50 cm (20 in.) on a bowhead whale.

o The thick layer of blubber results in a streamlined, fusiform (torpedo-shaped) body, making a whale energy-efficient for swimming.

o Blubber is an energy reserve. o A baleen whale's fusiform body shape and reduced limb size decrease

the amount of surface area exposed to the external environment. This helps conserve body heat.

• A baleen whale's circulatory system adjusts to conserve or dissipate body heat and maintain body temperature.

o Some arteries of the flippers, flukes, and dorsal fin are surrounded by

veins. Thus, some heat from the blood traveling through the arteries is transferred to the veinous blood rather than the environment. This countercurrent heat exchange aids whales in conserving body heat.

o When a baleen whale dives, blood is shunted away from the surface. This decrease in circulation conserves body heat.

o During prolonged exercise or in warm water a whale may need to dissipate body heat. In this case, circulation increases in veins near the surface of the flippers, flukes, and dorsal fin, and decreases in veins returning blood to the body core. Excess heat is shed to the external environment.

Social behavior

• Baleen whales are generally found singly or in loose associations rather than in large groups or families. Exceptions include migrating baleen whales, which may be found in small groups, and some species that mate in groups of several individuals.

• The strongest apparent bond between two individuals is between a calf and its mother.


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• Large numbers of individuals may congregate in feeding or calving areas

• Baleen whales exhibit sexual dimorphism. This means that there are obvious

physical differences between males and females. Mysticetes are rather unusual compared to other mammals in that female baleen whales are larger than males. Admittedly, this is extremely difficult to determine while at sea on a boat. This has come from many years of research, including the records of whaling ships, which routinely measured the size of their catches.

• Sexual dimorphism is common in odontocetes, with the males being larger than

the females. This is carried to extremes in the case of the sperm whale. The males may be 10-20 feet larger than the female!

• Mysticetes do not appear to form large tightly knit social groups. Some do form

groups, especially around breeding and feeding seasons. Occasionally they do form cooperative feeding groups, most notably in humpback whales. The closest bonds are those between mothers and calves.

• Toothed whales tend to form tight social groups. Some dolphins form groups, or pods, of over 1,000. Sometimes, the groups are divided by sex, with females and calves in so called "nursery pods" separate from the smaller male, or "bachelor" pods.

Individual behaviors

• Research into interpretation of baleen whale behaviors is ongoing. Some behaviors may be related to food-gathering, aggression, excitement, warning, visual inspection, or mating.

• When a whale throws its body out of the water and lands on the surface, it is called a breach. Sometimes breaches are repeated by the same individual several times in sequence.

Humpback whales are among the most acrobatic species of baleen whales. Breaching is a common behavior


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• Lifting the head vertically out of the water is called a spyhop.

• Some baleen whales slap their pectoral flippers, tail flukes, or head on the

surface of the water, which creates loud sounds underwater.

• Calves and adults have been seen pushing around objects such as logs, kelp, and debris.

• Various baleen whale species show characteristic behaviors.

o Humpback whales may be the most acrobatic species of baleen whales.

They engage in breaching, flipper-slapping, tail-slapping, spyhopping, charging other whales, and stroking another whale's flippers or flukes.

o Gray, fin, Minke, bowhead, and right whales commonly breach and

spyhop.

o Bowhead and right whales exhibit head- and body-slapping. Longevity Longevity for most whales is unknown. Longevity estimates include 30 to 90 years for blue whales, 90 to 100 years for fin whales, and up to 60 years for sei whales. Aging studies

• The absence of teeth (which can be used to approximate age in toothed whales and many other mammals) makes age estimation difficult.

• Research on baleen whale aging is ongoing. Researchers are analyzing growth patterns on the baleen plates and on the waxy ear plug of baleen whales to estimate age

Predators

• The major predators of baleen whales are killer whales. Working together, a group of killer whales may attack a baleen whale much larger than themselves.

o There are estimates that Antarctic Minke whales make up 85% of the killer whales' diet in that region.

o Evidence of unsuccessful attempts by killer whales include teeth scars remaining on the baleen whale's flippers and flukes.

o Large sharks may prey upon some baleen whales, particularly those that are ill, injured, or very young.

• The small (38 cm, or 15-in.) cookiecutter sharks use suction to attach themselves to whales, then they carve out a core of flesh with their large triangular teeth.

Human interaction

• Commercial and large-scale whaling.


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o The commercial whaling industry began to expand in the 12th century o The family of right whales (including right and bowhead whales) were so

named because whalers considered them the "right" whales to harvest. They have immense amounts of blubber and baleen; they are slow swimmers; they are coastal species; and their bodies float when dead.

o Whale oil was used for lighting, heating, and lubrication; as a base for the manufacture of soaps and paints; and in processing textiles and rope.

o Baleen was used to make corset stays, umbrella ribs, fishing rods, buggy whips, carriage springs, skirt hoops, brushes, and nets.

o As the right whales became rare, the whaling industry sought out more numerous species to harvest. In the 19th century, with improved hunting weapons and boats, faster species such as humpback, blue, and fin whales were killed in large numbers.

o Markets for whale products expanded to the 20th century, and more modern harpoons, explosives, and factory-type processing ships were used to hunt and harvest whales. Minke whales became a major target in the 1930's, when they were hunted by whalers because larger species were depleted.

• Indigenous and small-scale whaling.

o Indigenous peoples from various coastal areas hunt some species of baleen whales for subsistence. For instance, people in coastal arctic villages hunt small numbers of bowhead whales, Minke whales, and gray whales.

• Baleen whales may also be harmed by entanglement in fishing gear, heavy boat traffic, pollution, and competition with humans for food resources12.

This gray whale became entangled in monofilament fishing net and stranded on a beach in Southern California

12 Taken from SeaWorld Animal InfoBooks http://www.seaworld.org/animal-info/info-books/index.htm


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Satellite Tracking

Tagging and tracking marine animals can provide scientists with valuable information about animal location, behavior, and physiology as well as conditions in ocean ecosystems. Several systems are currently being used to track marine mammals, including satellite/GPS tracking systems, radionavigation tracking systems, and bioacoustic tracking systems.

Satellite transmitters, known as Satellite Relayed Data Loggers, are attached to

marine mammals with glue. These transmitters continuously collect, compress, and store data before transmitting the information to a satellite. The data are then relayed to ground stations, which process the information, compute the location from which the message was received, and place the location and raw data in a database. Satellite transmitters, however, usually last less than a year and can cost from about $3,000 to $6,000 per animal.

Radionavigation devices also store and transmit data. However, because radio

waves do not travel easily through water, data collected during dives must be stored for later transmission when the animal surfaces. In addition, transmission requires that an antenna be in the "line of sight" of the transmitter, making tracking over long distances difficult.

Bioacoustic tracking methods are based on the fact that different species

produce different sounds. Scientists can use underwater listening systems to track not only a variety of marine mammal species, but even individual animals. As with the radionavigation devices, bioacoustic tracking requires that researchers be within range of the animal in order to collect data13.

There are many implications of understanding animal tracking. Such information can be used for commercial, conservation, and scientific research.

13 Taken from OPB NOVA Teachers “Ocean Animal Emergency” http://www.pbs.org/wgbh/nova/teachers/activities/3517_ocean911.html


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Economically, animal tracking data is used by fishing and ecotourism industries as means to locate marine organisms. Conservation organizations also rely on tracking data to determine animal spatial movements thus influencing locations of urban development. Tracking data is frequently collected by researchers to gain knowledge of animal behavior such as migration between foraging, breeding, and nursery grounds.

Tagging

Scientists can learn a lot by tagging marine animals! Tagging animals provides information on their population size, migration patterns, and favorite habitats. A variety of tagging methods are available. Satellite Tagging

Satellite tags are small tags attached to marine animals in order to study their movement and migration patterns. Satellite tags are generally used to study larger animals, such as marine mammals, tunas and sharks. A satellite tag, which can fit in your hand, relays signals through satellites. This data is obtained by data systems on the ground. Battery life determines the quantity and quality of data received from the tag. Battery life decreases with each data transmission. Information relayed includes time, date, latitude, longitude, dive depths, dive durations, and surface times. Two types of tags exist. The pop-up satellite archival tag transmits all the data at one time, when the battery dies. The other type of satellite tag collects data while the animal is underwater and then transmits this data by antennae when it surfaces. Satellite tags can last from a few days to many months. Satellite tagging provides crucial information at a high cost; one tag can cost around $3500.

WhaleNet uses satellite transmitters that send signals to satellites maintained by the ARGOS (Advanced Research and Global Observation Satellite) System in Largo, Maryland and Talouse, France. A number of the U.S. National Oceanographic and Atmospheric Administration's (NOAA) weather satellites, circling the earth, have instruments attached. These instruments collect, process and disseminate environmental data relayed from fixed and mobile transmitters worldwide. What makes this system unique is the ability to geographically locate the source of the data anywhere on the Earth.

Archival Tags

Archival tags are small tags implanted or attached to a marine animal. These tags record information such as depth, light, water temperature and internal body temperature. They can even record the heart rate and the swimming speed of some marine mammals. Archival tags are unique because they provide information about the oceanographic environment in which the animal is traveling. This information is important for determining how changing oceanic conditions relate to an animal's behavior, movement patterns and physiology. Although Archival tags provide essential information, the data can only be obtained when the tag is recovered. For this reason, scientists tend to study animals with either a predictable movement pattern or animals likely to be caught again in fisheries, such as fish and sharks14.

14 Taken from Teaching Engineering “Marine Animal Tracking” http://teachengineering.org/view_lesson.php?url=http://www.teachengineering.org/collection/duk_/lessons/duk_marine_musc_less2/duk_marine_musc_less2.xml


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Why Use Technology in Scientific Research? In order to make more knowledgeable decisions about our uses of our environment, we must better understand it and the organisms, which use this environment. Recent innovations and improvements in a number of technologies are allowing scientists to answer more complex questions about animals in their natural environments. The advancement of these technologies comes at a critical time when scientists want to monitor many different animals around the world because of concerns about their populations, health, or issues related to international disputes.

To better understand animals we need to obtain information about their life histories including their long and short-term movements, as well as how their movements may be affected by changing environmental conditions. We need to study the factors relating to their migrations. In order to protect highly migratory animals we must know the locations of all their habitats, how they use each habitat, when they travel between them and the routes they take.

However, this information is difficult to obtain particularly for marine animals.

Until recently much of the information about marine animals was from catch and incidental kill data, strandings or direct observations. The recent technological developments of radio and then satellite tags, as well as satellite images, have provided rich new information about marine animals and their habitats.

For example, in 1996 a group of Marine Biologists aboard a ship in the Gulf of Mexico used maps of ocean currents, produced with satellite-gathered data, to help locate and count sperm whales. Based on evidence that whales prefer to feed in the edges of cyclonic eddies, they viewed satellite data which provided them with a picture of where these oceanographic features were located. They used this information to find the whales more quickly which aided them in taking a visual and acoustic census of these marine mammals. They were then able to learn more about their habitat in areas potentially affected by oil and gas activities. The satellite-gathered data, developed to study global ocean circulation, provided a bonanza of information for these marine biologists. Scientists are continuing to find new applications for this satellite data.

Satellite tagging is a relatively new method in the study of organisms in their


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own habitat. It allows scientists to investigate animal movements, particularly in the case of animals that travel long distances or dive to great depths; as well as animals that are difficult to observe. The use of satellite-linked transmitters has enabled field biologists to overcome many of the difficulties associated with studying cetaceans and other marine animals at sea.

Why use satellite tags to study whales and other marine animals? If we can determine where the whales and marine mammals travel, where they

feed and where they give birth, more informed decisions can be made about how humans use these same areas. For example, war games and other military maneuvers can be moved from critical habitats. Commercial uses of the ocean can be managed more effectively, such as moving navigation channels, controlling when the channels are used, limiting the speed of vessels or providing early warning information for mariners so they can avoid disturbances or collisions.

Learning more about the diving behavior of marine animals can reveal whether

an animal is at risk of becoming entangled in certain types of fishing gear. Fishing management decisions can then be made about where and when to fish to minimize incidental catch and mortality of whales and other marine mammals.

With the recent advances in electronic sensors and transmitters, marine

mammal tags have taken a quantum leap in the amounts and types of data they can provide. Tags with a variety of sensors can be attached to animals to learn about the biology of the animal and about the environment in which the animal lives.

In addition, satellite tag studies have been conducted on released rehabilitated

animals, that were rescued after stranding. Although these animals may not behave as if they are fully wild, the tags can provide information about the animal after release, such as its survival. Also these tags provide an opportunity to test the satellite transmitters, and to correlate the tag's data with oceanographic and remote sensing data collected from other sources.


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With the use of satellite tags, we gain important insights into the animal's use of its habitat, range of movements, birthing areas and more. This gives us more insights into the natural history of the animal and enables more intelligent and meaningful decisions about our uses of the oceans. Understanding the full range of an animal's habitat requirements can allow us to better manage and protect those areas, which will increase the potential for recovery and for an improved coexistence in this shared marine environment. How Satellite Tags Work

Holding a satellite tag in the palm of your hand it is difficult to imagine that this little device is powerful enough to send a signal to satellites orbiting 1000kms above the surface of the earth. This signal is relayed by the satellite to a data processing computer back on Earth and can then be transferred electronically around the globe. WhaleNet uses satellite transmitters that send signals to satellites maintained by the ARGOS System in Largo, Maryland and Talouse, France. A number of the U.S. National Oceanographic and Atmospheric Administration's (NOAA) weather satellites, circling the earth, have ARGOS instruments attached. These instruments collect, process and disseminate environmental data relayed from fixed and mobile transmitters worldwide. What makes ARGOS's system unique is the ability to geographically locate the source of the data anywhere on the Earth.

Data is collected by the tag while the marine animal is underwater and then

transmitted when the animal surfaces. The tag has an antennae which is used to send a signal each time the animal surfaces. Information relayed includes time, date, latitude, longitude, dive depths, dive durations, amount of time at the surface in the last six hours and quality of the transmission. The ARGOS instruments detect the tag's signal when the satellite passes overhead. The location fix of the animal in relationship to the track of the satellites, with ARGOS instruments, affects how many satellites passes are made over the animal's tag in a 24 hour period. Each pass may last

Locations of two satellite-tagged adult males short-finned pilot whales tracked over 4 and 9 days in 2007. From Schorr et al. (2007).


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between 2 and 12 minutes, depending on the location of the satellite in relation to the animal. The animal must be at the surface at the time of the pass for a successful transmission to take place. Therefore, each day there are a limited number of short opportunities, or maybe no opportunities, for a signal to be transmitted from an animal's tag to a satellite.

The tag stores data for four to six hour time periods while collecting recent

data. The information transmitted by the tag transmitter depends upon the programming of the tag and the data distribution system. The data is transmitted from the tag in the form of digital codes, which must be deciphered. WhaleNet uses different types of tags, made by three different companies, with different programming set-ups. The data collected and the way the data is decoded can be different for each tag.

In order to get a fix or position reading it is necessary to receive two or more

transmissions from the satellite tag. If at least two messages are received during one pass, computers at the earth station can calculate a location for the transmitter. However, locations based on only two messages are not very accurate. Ideally, locations should be based on three or more messages. In these cases there is a good chance the animals is actually within 1 km of the location calculated. The need for multiple readings to determine position can result in times when the location cannot be reported. You might get none, one or 12 fixes in a day. Other data, such as dive data, can be obtained in just one transmission. The transmitter is programed to turn itself on and off to conserve battery life. It has a saltwater switch so that it only transmits while it is exposed to air. The signal is too weak to penetrate water. This limits the use of satellite technology to species that spend time at the water's surface or come to the surface regularly. Therefore these devices are particularly appropriate for studying marine mammals that must come up to breathe. The tag is programmed to think it is dry when it sends five signals without wetting the saltwater switch (about seven minutes out of the water).

Battery life affects how much and the quality

of data received from a tag. Battery life varies depending upon size, temperature, depth or pressure and corrosion by the saltwater. Also, data transmission uses up the battery. Therefore, the more transmissions, the shorter the battery life. WhaleNet has used various batteries with its tags in an effort to extend the life expectancy of the tag. Our tags have lasted up to nine months. Some tags stopped sending signals prematurely. Ideas about why this occurred include problems with salt water getting into the tag, the antennae breaking or the animal knocking the tag off.

How Satellite Tags are Attached Attachment of the tag varies depending upon the animal. In the case of seals and


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turtles the tag is glued to the fur or shell. When a seal molts the tag falls off. Some tags have been attached with suction cups or bolts. With whales the tag is attached by partially implanting a barb into the blubber layer at a slight angle, to a depth of approximately 10 cm. Ideally it is placed high on the back of the whale, directly behind the blow hole. These tags are deployed using a compound crossbow. A study by the Minerals Management Society determined that this does not cause serious stress or pose a health risk to the whale. The tagging team goes out in a 4 meter rigid-hull inflatable equipped with an outboard motor in order to get close enough to the whale to implant the tag. Many tags placed on whales have stopped transmitting in only a few days. It appears that some of the tags WhaleNet has placed on whales have been rejected, falling off and sinking to the bottom of the ocean shortly after they were attached. This may be caused by the whale's immune system. We are working on ways to get a more secure attachment without harming the whale. The durability of the tag attachment and antennae are still areas that need improvement. Tag designers are also working on developing more hydrodynamic shapes for the tags. For example, on turtles the tag slants on the front face creating less drag as the turtle swims. Satellite tagging is very expensive. The cost of the tag itself ranges from $3,500 to $5,000. There are also the costs associated with attaching the tag. In the case of a whale these costs include a boat, crew, fuel, and travel to the tagging location. And there is a charge for the data transmission time. In order to recover some of this cost and equally important the tag, manufacturers place their name and address on each tag so that if it is recovered it can be returned15.

15 Taken from WhaleNet Satellite Tag Information http://whale.wheelock.edu/whalenet-stuff/stop_cover.html#tags


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Gray Whale Migration

The Gray Whale Obstacle Course Once hunted to the brink of extinction, the gray whale has made

an amazing comeback in the last 80 years. But in 1999 and 2000, these unique creatures, which l ive along the West Coast of North America, began to mysteriously disappear by the thousands. Their population dropped by one-third.

Gray whales have the longest migration route of any mammal --

8,500 to 12,000 miles -- and during their journey they pass some of the world 's biggest cit ies, along some of the most polluted coastl ines. In The Gray Whale Obstacle Course, Jean-Michel Cousteau and the Ocean Adventures team travel the length of this migration, from the warm waters of Magdalena Bay in Baja California, Mexico, where the gray whales give birth, nurse their calves, rest and play before their long journey north, to the nutrient-rich feeding grounds of the Bering Sea in Alaska. The team searches for clues about this resi l ient, yet threatened species to gain a better understanding of the increasing challenges, both natural and man-made, that gray whales face along the way.

The journey of Jean-Michel and his team begins with a visit to the

gray whales ' Arctic feeding grounds. The area is huge -- about the size of Maryland and Delaware combined. In the summer months, the region experiences nearly 24 hours of sunlight, which fuels an explosion of t iny plant and animal growth. When the whales arrive here, they feast. They haven't eaten for seven months, and they are far thinner than when they left these feeding grounds. Here, on a dive in the frigid waters, the Cousteau team collects mud from the ocean floor to find amphipods, the tiny creatures that are the staple of the gray whale 's diet. Forty-five feet long and weighing 30 to 40 tons, gray whales eat one ton of amphipods a day. In fact, over the approximately f ive months that the gray whales spend in the Alaskan waters, each whale eats about 396,000 pounds of amphipods. Instead of teeth, gray whales have long, thin plates of baleen that hang from their upper jaw. Baleen is made of keratin, the same material that makes up human fingernails. To feed,


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the whales take in large mouthfuls of water, then use their tongue to squeeze the water out through the closely layered plates of baleen, which act l ike fi lters. The amphipods get stuck in the baleen, and the whales use their tongue to l ick off the tiny critters.

At this Arctic feeding ground, the Cousteau team wonders: Could the decline of the whales be l inked to their food source? Or is it perhaps connected to other obstacles they face along their migration path? To explore these questions, the team meets the whales at the southern point of their journey, in Baja California, Mexico, and travels with them northward to observe, document and understand the hurdles these creatures must overcome each year.

In the 1880s and again in the early 1900s, whalers in Mexico hunted the gray whale almost to extinction. Then in the 1930s, the whales were protected, and in the 1970s, they were l isted as an endangered species. Early whalers referred to the gray whale as the "devilf ish" because of its reputation for f ighting back and overturning boats when attacked. Ironically, today gray whales are the friendliest of all whales. In the safety of Baja 's protected San Ignacio Lagoon, gray whales have been regularly approaching people since 197216.

Navigating the Long Way Home

Imagine this: You 're in Los Angeles, you 're hungry and your next meal is in New York City. To get to it, you have to cross the continent. There aren 't any maps or road signs, and the weather 's constantly foggy, making it hard to see. How will you make your way?

This seemingly impossible scenario is s imilar to the task that migrating whales face when they make their journeys. They eat very l ittle along the way, it 's diff icult for them to see and, of course, there aren 't any road signs. Or are there? Scientists who study whales believe the animals use a combination of senses to find their path, in a way that helps them "see" the ocean floor, spot landmarks along the way and

16 Taken from Jean-Michel Cousteau Ocean Adventures “About: The Gray Whale Obstacle Course” http://www.pbs.org/kqed/oceanadventures/episodes/whales/about.html

One theory is whales can use oilrigs as a point of reference for navigation


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navigate in the proper direction.

Sounding It Out Enthusiasts have known for decades that whales use noises to communicate. Whales are divided into two groups, and each uses sound differently. Toothed whales, l ike orcas and dolphins (which are in the whale family), use a form of sonar called echolocation, making clicks and pops that reflect back to them, tell ing them the locations of things around them. Baleen whales use low-frequency calls that have the same effect but can travel long distances. Until recently, scientists believed that baleen whales didn 't use sonar to navigate, but new research is revealing that they most l ikely do.

Our understanding of these creatures ' use of acoustics began to

deepen in the early 1990s, when researchers at Cornell University started using a Cold War spy technology to tune in to baleen whales. The U.S. Navy 's Sound Surveil lance System (SOSUS) is a network of underwater microphones, called hydrophones. The Navy used it to l isten for Soviet submarines, probably never anticipating that it would someday be used to eavesdrop on marine mammal.

The Cornell researchers learned that the trick to interpreting

data gathered by SOSUS is to think about it from a whale 's perspective. Water conducts sound much more efficiently than air, and whales can hear much better than humans. When scientists analyzed the sounds picked up by SOSUS - with the scale of the ocean in mind - they discovered that whales send their vocalizations over thousands of miles to communicate and navigate during migration and that their calls took place in a time frame much different from that of human communication. A blue whale, for example, can take up to two minutes to sing just one note of its song. The frequency it s ings at is too low to be heard by the human ear, but is one that can travel great distances through water. In essence, a whale 's f ine-tuned abil ity to make and use sound is akin to our sense of sight; but it is sound, rather than l ight, that allows them to "see" the world around them.

There is some evidence that whales use their songs not only to

orient themselves, but also to move together as a group. Researchers see pods of whales spread out over many miles moving together as if they were choreographed. Scientists also think whales may have


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acoustic memories that function l ike our visual memories. In other words, when they 've "heard" a certain route, they can search for familiar landmarks to guide them on their repeat migratory journeys. Unfortunately, just as scientists are gleaning more new information by l istening underwater, they are finding it harder to isolate the whale sounds from the myriad and increasing man-made noises polluting the seas. Sound from shipping vessels, oil exploration, mil itary sonar, and even private boats and whale-watching expeditions is f i l l ing in what used to be quiet space in the ocean. And it 's affecting the whales. When their songs are drowned out by other noises, the distance their calls can travel shrinks, making the calls less useful for communication and navigation. In addition, some of the sonar used by the military to keep an eye on movements in the ocean is thought to be the same frequency as that of some whale calls, and therefore it might confuse the whales or interfere with their communication.

Noise pollution may even affect whale breeding: The males of

some whale species court females by singing to them across many miles. If the males ' calls are swallowed up in the din of other undersea noises, the females won't hear them and may miss breeding opportunities.

Magnetic Migrations Along with their sonar, whales have other tricks they employ to keep themselves on track. Many researchers believe that whales and other migrating animals have a magnetic sense that helps them know which direction they 're moving. Scientists know that a substance called biomagnitite helps many birds migrate by making them sensitive to changes in the earth 's magnetic f ield. Cetaceans, the animal family to which whales belong, have biomagnitite in the retinas of their eyes, which may function in the same way.

The intensity of the earth 's magnetic f ield fluctuates across the globe, and an animal able to sense these changes could potentially use them like a map. There is some evidence that toothed whales do this. Most magnetic f ield l ines in the ocean run the same direction as the coastl ine. But in some places, they turn and run perpendicular to the


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shore. A whale riding this magnetic "road" might be more l ikely to strand in areas where the path turns. When researchers studied the magnetic f ield l ines around beaches where groups of whales have repeatedly been found stranded, they found that in each instance, the magnetic paths turned shoreward.

Unfortunately, it 's very diff icult

to study sensitivity to magnetism in whales that are going about their normal business and not stranding on shore, so the question of magnetic navigation remains unclear. But most whale researchers believe it plays some role in navigation.

Eye, Aye! Last, and possibly least, whales may occasionally surface to take a look around. This behavior is called spy hopping, which is something l ike when people tread water. The whale ti lts its whole body vertically, with its head out of the water, and flaps its tail to keep itself in position. It can stay l ike this for 15 to 30 seconds, slowly turning and surveying the landscape. These surveys may help the whale see how close it is to shore or to oncoming ships it has been hearing in the distance. The whale 's yearly journey is challenging enough to warrant the recruitment of many senses and skil ls. It 's l ikely that learned behavior, communication between whales and all of a whale 's senses play a role in steering these giants through their migration routes. Not being able to get inside the mind of these mammoth mammals, though, we may never be able to explain exactly how they succeed in making their incredible trips17.

17 Taken from Jean-Michel Cousteau’s Ocean Adventures “In depth: Whale Navigation” http://www.pbs.org/kqed/oceanadventures/episodes/whales/indepth-navigation.html


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Human Impact on Whales

Cetaceans are in peril and certain species are facing extinction. Today “seven out of the 13 great whale species are still endangered or vulnerable after decades of protection, as are further 17 small whale, dolphin and porpoise species or populations” (WWF source, May 2007).

While hunting and whaling have been major causes of the cetaceans’ endangerment, they now face a greater threat than ever before due to other human activities that have caused terrible environmental changes, for example, climate change (in the form of global warming), chemical and noise pollution, overfishing (depletion of their food resources), increased sea traffic, etc.

Manatees are also victims of human disturbances: they are slashed through and killed by boat propellers (25% of deaths), or are the victims of fishhooks, litter and other objects they accidentally swallow. They are losing their habitat to humans as they live in coastal shallow waters. They are suffering from environmental changes and pollution. In Florida there are only 3,000 left. Cetacean populations are biologically unable to withstand such increased rates of unnatural mortality as they cannot recover quickly: they mature late, reproduce at a slow rate, and take care of their young for an extended period of time. Causes of Endangerment and Death Cetacean

• Climate change in the form of global warming has many consequences including habitat destruction, food supply depletion, and the release of chemicals into the water. Krill, the baleen whale’s basic food, is in decline due to the melting of the sea ice cover in the polar regions. Polar ice cover melting is also releasing old chemical pollutants into the sea.

• Commercial catch: By-catch, direct catch, whaling, live catch for display, culling (cetaceans are culled as they are believed to eat fish caught by fishing industry.)

• Entanglement in fishing nets and gear that kills globally an estimated 300,000

cetaceans (small and great alike) annually is the greatest cause of cetacean mortality. They can also die of starvation if the net gets caught in their baleen plates.

• Overfishing leads to primary food resource loss that in turn leads to starvation.

• Chemical pollution (industrial, domestic, agricultural) contaminates cetaceans and the prey they feed on. Body, blubber and meat are poisoned by contaminated water and prey. Impact on health and reproduction. Many diseases, cancer, sterility and deformities. Litter such as plastic bags are a real cause of asphyxia.


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• Noise pollution due to increased vessel traffic, ship and military sonars,

explosives, underwater construction, offshore oil drilling, seismic testing for oil and other related activities alter the perceptions of cetaceans, who depend on sound and magnetic waves for navigation, hunting, communication, etc.

• Collision with commercial ships, super tankers, merchant vessels, recreational boats, military vessels, oceanographic researcher boats, etc. A major threat for great whales18.

18 Text and proceeding image taken from Dolphins and Whales Tribes of the Ocean 3D http://www.dolphinsandwhales3d.com/education/d&w3d_educatorsguide.pdf


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Ocean Color If someone were to ask you what the color of the ocean was, chances are that you would answer that is was blue and for most of the world's oceans, your answer would be correct. We see color when light is reflected by the things around us. White light is made up of a spectrum or combination of colors, as in a rainbow of many different wavelengths. The longer wavelengths of light are red, the shorter wavelengths, blue. The order of the colors in the rainbow - Red, Orange, Yellow, Green, Blue and Violet reflect (no pun intended) the order of their wavelengths from longest to shortest. When light hits the surface of an object, these different colors can be reflected or absorbed in differing intensities depending on the unique properties of the material on which the light is shining. The color we see depends on which colors are reflected and which are absorbed. For example, a book that appears red to us absorbs more of the green and blue parts of the white light shining on it, and reflects the red parts of the white light. The same applies to the ocean. When sunlight hits the ocean, some of it is reflected back directly (sunglint), but most of it penetrates the ocean surface and interacts with the water molecules that it encounters. Most of the light that is scattered back out of clear, open ocean water is blue while the red portion of the sunlight is quickly absorbed very near the surface. However, there are many things in addition to just water molecules in the ocean and these things can change the color that we see. In coastal areas, runoff from rivers, resuspension of sand and silt from the bottom by tides, waves and storms and a number of other things can change the color of the near-shore waters. However, for most of the world's oceans, the most important things that influence its color are PHYTOPLANKTON. Phytoplankton are very small, single-celled plants, generally smaller than the size of a pinhead that contain a green pigment called chlorophyll. All plants (on land and in the ocean) use chlorophyll to capture energy from the sun and through the process known as photosynthesis convert water and carbon dioxide into new plant material and oxygen. Although microscopic, phytoplankton can bloom in such large numbers that they can change the color of the ocean to such a degree that we can measure that change from space. The basic principle behind the remote sensing of ocean color from space is this; The more phytoplankton in the water, the greener it is....the less phytoplankton, the bluer it is.19.

We see color when light is reflected by objects around us. White light is made up of a spectrum or combination of colors, as in a rainbow. When light hits the surface

19 Taken from NASA Ocean Color “Monitoring the Earth from Space with SeaWIFS” http://oceancolor.gsfc.nasa.gov/SeaWiFS/TEACHERS/sanctuary_3.html


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of an object, these different colors can be reflected or absorbed in differing intensities. The color we see depends on which colors are reflected and which are absorbed. For example, a book that appears red to us absorbs more of the green and blue parts of the white light shining on it, and reflects the red parts of the white light. When we look at the ocean from space, we see many different shades of blue. Using instruments that are more sensitive than the human eye, we can measure carefully the fantastic array of colors of the ocean.

Different colors may reveal the presence and concentration of phytoplankton, sediments, and dissolved organic chemicals. Phytoplankton are smaIl, single-celled ocean plants, smaller than the size of a pinhead. These plants contain the chemical chlorophyll. Plants use chlorophyll to convert sunlight into food using a process called photosynthesis. Because different types of phytoplankton have different concentrations of chlorophyll, they appear as different colors to sensitive satellite instruments such as the Sea-viewing Wide Field-of-View Sensor (SeaWiFS). Thus, looking at the color of an area of the ocean allows us to estimate the amount and general type of phytoplankton in that area, and tells us about the health and chemistry of the ocean. Comparing images taken at different periods tells us about

changes that occur overtime. Why are phytoplankton so important? These small plants are the beginning of the food chain for most of the planet. As phytoplankton grow and multiply, small fish and other animals eat them as food. Larger animals then eat these smaller ones. The ocean fishing industry finds good fishing spots by looking at ocean color images to locate areas rich in phytoplankton. Phytoplankton, as revealed by ocean color, frequently show scientists where ocean currents provide nutrients for plant growth. In addition, the plants show where pollutants poison the ocean and prevent plant growth, and where subtle changes in the climate-warmer or colder more saline or less saline-affect phytoplankton growth. Since phytoplankton

depend upon specific conditions for growth, they frequently become the first indicator of a change in their environment20.

The "color" of the ocean is determined by the interactions of incident light with substances or particles present in the water. The most significant constituents are free-floating photosynthetic organisms (phytoplankton) and inorganic particulates. Phytoplankton contain chlorophyll, which absorbs light at blue and red wavelengths and transmits in the green. Particulate matter can reflect and absorb light, which reduces the clarity (light transmission) of the water. Substances dissolved in water can also affect its color.

20 Taken from SeaWIFS Project “The Living Ocean Teacher’s Guide” http://oceancolor.gsfc.nasa.gov/SeaWiFS/LIVING_OCEAN/


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The phrase "ocean color data" refers to accurate measurements of light intensity at visible wavelengths. As ocean color data is related to the presence of the constituents described above, it may therefore be used to calculate the concentrations of material in surface ocean waters and the level of biological activity. Ocean color observations made from Earth orbit allow an oceanographic viewpoint that is impossible from ship or shore -- a global picture of biological activity in the world's oceans21.

21 Taken from Goddard Earth Sciences Data and Information Center “Ocean Color” http://daac.gsfc.nasa.gov/oceancolor/


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Fish Scales

Do all fishes have scales? No. Many species of fishes lack scales. All the clingfishes (family Gobiesocidae) for example, are scaleless. Their bodies are protected by a thick layer of mucous. Why do fish have scales? The primary purpose of scales is to give the fish external protection. How many types of scales are there? There are four main kinds of scales and numerous variations of each kind. Placoid Cosmoid

Ganoid Cycloid and Ctenoid

Are all scales the same size? No. Scale sizes vary greatly between species. Some fishes, such as the freshwater eels have tiny embedded scales. Fishes such as the tunas have tiny scales often found in discrete areas of the body. Many fishes such as the Coral Snappers have medium sized scales whereas the scales of others such as the Tarpon, Megalops cyprinoides are large enough to be used in jewelery. The scales of the Indian Mahseer, Tor tor are known to reach over 10 cm in length. How old is a fish scale? As cycloid and ctenoid scales increase in size, growth rings called circuli become visible. These rings look a little like the growth rings in the trunk of a tree. During the


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cooler months of the year the scale (and otoliths) grows more slowly and the circuli are closer together leaving a band called an annulus. By counting the annuli it is possible estimate the age of the fish. This technique is extensively used by fisheries biologists. Can a fish have more than one type of scale? Yes. Some species of flatfishes (flounders, soles, etc) have ctenoid scales on the eyed side of the body and cycloid scales on the blind side. Can scale type vary with sex? Yes. In some species of flatfishes, males have ctenoid scales and females have cycloid scales.

Investigating the age and life span of fishes is especially difficult, if not impossible, from only brief observations in the wild. Fortunately, individual fishes keep a permanent record of their life history in some of the hard tissues of their bodies. As a fish grows, its scales must grow as well in order to keep its body covered. If a scale is lost or removed, a new one will replace it. The process is similar to the way a tree grows, but while trees add one ring per year, a fish scale may gain many rings (two, three or up to 20) in a single year. The basis of most aging techniques in fishes is the annulus or year mark. In Ontario, where there are distinct seasonal changes, clear annular zones form during the colder months of winter. The focus is the first part of the scale to develop. A ridge called the circulus is laid down around the focus (appears as a dark ring) as the fish continues to grow. Several circuli are added to the scale each year, thus increasing the scale's size. When conditions are good, as in late spring and summer, warmer water temperatures and more available light stimulate an increase in the metabolism of the fishes and circuli are formed further apart. When conditions are harder, as in winter, growth slows down and circuli, if formed, are much closer together and sometimes appear broken or fragmented. The rings create a zone called the annulus, which indicates the termination of that year's growth. The age of the fishes is determined by counting the number of annuli22.

By determining the age of individual fishes, scientists can begin to gain some insight into the population as a whole. The rate at which fishes grow in a given lake or stream can be determined and compared to expected or normal growth rates. Since the onset of sexual maturity in fishes tends to slow the growth rate down, scientists can estimate the age at which a species reaches sexual maturity (which can be verified by experts during the spawning period). This can help in the development of fishing regulations to ensure that sufficient numbers of fishes can reproduce at least once before being caught by anglers or a commercial fishery. Fish populations stressed by humans tend to show typical age distributions. A fish population suffering from overfishing or excessive natural predation will lack older fish, and younger fish will predominate. What older fish that occur will tend to be larger for their age than in an unstressed population. If the situation continues, then young fish will decline as well since the reproducing fish are gone. A fish population of predominantly older fish may be underfished, or the spawning or nursery habitat may be lacking. Each species of fish has its own unique scales. Thus, fish scales can be useful as evidence when prosecuting someone with fishing out of season, or when trying to identify what kind

22 Taken from the Australian Museum Fish Site http://www.amonline.net.au/fishes/what/scales/index.htm


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of fish another fish might be eating. Some fishes can be aged more reliably by other body parts. Annual growth rings are laid down on vertebrae, otoliths (ear-stones), pectoral fin rays, dorsal fin spines (e.g., walleye) and cleithrum (cheek) bones (e.g., for northern pike)23.

A critical piece of data needed for good fisheries management is the age

distribution and growth history of fish. These can be determined by examining fish scales or other boney parts of a fish such as the otoliths (ear bones) or a section of fin spine (catfish). Division biologists most often use scales because it is a non-lethal method. From 3 to 5 scales are removed from each fish and placed in a coin envelope. Data about each fish is also recorded on the envelope: date, location, species, length, and weight. Sex is also recorded if known. Scales show the history of the fish in a fashion similar to the rings of a tree. Scales get larger as the fish grows by adding to the outside edge. Because fish are cold-blooded and grow very little during winter, a thicker ring is formed, giving a year mark. Therefore, biologists can use scales to determine the age of many fish species. Fish growth is variable and depends mainly on food supply and water temperature. Typically in Delaware, a 3-year old largemouth bass is about 12 inches, but in a pond with a poor food supply, a 3-year old fish may be only 5 inches long. Scale samples are collected from many fish and averaged as individual fish can show variation in growth.

Because a scale holds the growth history of the fish, it can also be used to

determine length at all ages up to the current one. The placement of the winter rings on the scale is proportional to the total length of the fish. For example, if a 3-year old, 12 inch bass had the first ring about halfway from the center to the scale edge, that fish was about 6 inches at one year. If the first ring was about a third of the way from the center, the fish was about 4 inches. Since striped bass surveys are conducted during the spring spawning season, sex is easily determined. Often fish growth differs between males and females, as is the case with striped bass. Age and growth data are especially important when managing a fish species, like the striped bass, which migrates in and out of its waters and is targeted by both recreational and commercial fishermen24.

23 Taken from Canadian Wildlife Federation “Wild Education” http://www.wildeducation.org/programs/fish_ways/activity/scales.asp 24 Taken from Delaware Fish & Wildlife “Fish Scales Tell a Story” http://www.fw.delaware.gov/Fisheries/Documents/agegrowth.pdf


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Useful Websites

Whale Sound Whale Sounds http://www.whalesounds.com Discovery of Sound in the Sea http://www.dosits.org PBS/Jean-Michel Cousteau Ocean Adventures http://www.pbs.org/kqed/oceanadventures/ Whales Whaling – Greenpeace International http://www.greenpeace.org/international/campaigns/oceans/whaling American Cetacean Society http://www.acsonline.org/ Pacific Whale Foundation http://www.pacificwhale.org/ National Marine Mammal Laboratory http://www.afsc.noaa.gov/NMML/ The Marine Mammal Center http://www.tmmc.org/ OSU Marine Mammal Institute http://mmi.oregonstate.edu/ Ocean Color Satellite Observations of Ocean Color http://www1.whoi.edu/satellite.html SeaWIFS Teacher Resources http://oceancolor.gsfc.nasa.gov/SeaWiFS/TEACHERS/ Northwest Association of Networked Ocean Observing Systems http://www.nanoos.org/education/marine_science/marine_science_for_ocean_observing.php Fish Scales Oregon Department of Fish & Wildlife Scale Analysis Project https://nrimp.dfw.state.or.us/CRL/default.aspx?pn=FS Hubbard’s Fish Anatomy http://fishanatomy.net/


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Other Resources

Videos/Audio National Geographic Animal Videos http://video.nationalgeographic.com/video/player/animals/ Whale Video Gallery at Whalewatch.com http://www.whalewatch.com/photos/video.php Whale Video and Sound Files at the Whale Center of New England http://www.whalecenter.org/av.htm Books Begrano, Andrea (2005) Aquatic Food Webs: An Ecosystem Approach Berta, A.B., Sumich, J.L., Kovacs, K.M (2006). Marine Mammals: Evolutionary Biology Cerullo, Mary (1999) Sea Soup: Phytoplankton Cerullo, Mary (1999) Sea Soup: Zooplankton Farr, Daniel (2002), Indicator Species, in Encyclopedia of Environmetrics Lauber, Patricia (1991) Great Whales: The Gentle Giants Omori, M.; Ikeda, T. (1992). Methods in Marine Zooplankton Ecology Thurman, H. V. (1997). Introductory Oceanography. Articles Cheung, C.H.Y, Chaillé, P.M, Randall, D.J, Gray J.S, Au, D.W.T (2007). The use of scale increment as a means of indicating fish growth and growth impairment. Aquaculture 266 102-111 Fish Scales From Norway Show Fate of Atlantic Ocean – Science Daily http://www.sciencedaily.com/releases/2008/05/080531092343.htm NASA Satellite Sees Ocean Plants Increase – Science Daily http://www1.whoi.edu/satellite.html Satellite Video Shows Struggling Seas – LiveScience http://www.livescience.com/environment/071024-earths-oceans.html Tyack, P.L (1999). Communication and cognition. p287-323 in Reynolds & Rommel “Biology of Marine Mammals”


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Tyack, P.L (2000). Functional aspects of cetacean communication. p270-307 in Mann et al “Cetacean Societies: Field Studies of Dolphins & Whales” Additional Educational Resources PBS Ocean Adventures For Educators http://www.pbs.org/kqed/oceanadventures/educators/ Brain Pop http://www.brainpop.com/ Hatfield Marine Science Center Education http://hmsc.oregonstate.edu/education/ The Bridge http://www.vims.edu/bridge/ National Marine Educators Association http://www.marine-ed.org/ Northwest Aquatic and Marine Educators http://www.pacname.org/